As a heat-dissipating member (heat spreader) for a semiconductor element, a member utilizing a composite material made of a metal and a non-metal inorganic material (representatively, ceramics) such as Al—SiC, that is, a composite member, has been used. In recent years, a magnesium-based composite material including magnesium (Mg), which is lighter in weight than aluminum (Al), or an alloy thereof, as a matrix metal has been under consideration for the main purpose of achieving a lighter-weight composite member (see Japanese Patent Laying-Open No. 2010-106362 (Patent Document 1)).
The above composite member is representatively a flat plate member, and is utilized as a heat-dissipating member. Specifically, a semiconductor element and the like are mounted on one surface of the composite member serving as a heat-dissipating member. Further, the composite member is fixed to a cooling device such as a water cooler with bolts or the like such that the other surface thereof contacts the cooling device.